The characterization of parent rocks currently rests essentially on determining the quantity and quality of hydrocarbons likely to be generated when they are buried. Such a characterization is insufficient, since it does not take into account the ability the rocks possess to possibly expel the generated products. However, it is clear that, in a sedimentation basin, the presence of an oil (or gas) accumulation is strongly conditioned by the possibility the hydrocarbons originally possess for possibly leaving the parent rock containing these hydrocarbons.
The ability for expelling produced hydrocarbons seems to be an essential parameter in determining good parent rocks capable of easily expelling the hydrocarbons they have produced, as opposed to poor parent rocks capable of expelling fuel or no hydrocarbons. Currently, there are no means enabling this parameter to be defined. The present invention offers a method and device allowing the rocks to be classified according to their ability to expel hydrocarbons in accordance with the conditions of a migration test conducted on rock samples in the laboratory.